Electrodeposition of a corrosion resistant decorative nickel-chromium coating and products thereof



United States Patent 3,268,308 ELECTRODEPOSXTION OF A CORROSION RESIST-ANT DECORATIVE NICKEL-CHROMIUM COAT- ING AND PRODUCTS THEREOF ThaddeusW. Tornaszewski, Dearborn, and Henry Brown,

Huntington Woods, MiClL, assignors, by mesne assignments, to The UdyliteCorporation, Warren, Mich., a corporation of Delaware No Drawing. FiledMar. 1, 1963, Ser. No. 262,199 17 Claims. (Cl. 29-194) This invention isfor improvements in or relating to decorative nickel electroplating, andmore particularly relates to (l) the electrodeposition ofsub-microscopic satin-textured to macroscopic satin-texturedfine-grained nickel plate from semi-bright and bright nickel platingbaths containing dispersed therein fine bath-insoluble particles, and(2) to the exceptional corrosion resistance of these deposits whenover-laid with a thin chromium plate.

The decorative fine-grained nickel deposits of this invention havevarious degrees of brightness, or of uniform smokiness, or of uniformsatin-sheen depending mainly on the concentration and particle size ofthe dispersed fine powders in the semi-bright or bright nickelelectroplating baths, the concentration of the nickel brighteners, thedegree of agitation of the cathode or the solution, the brightness andsmoothness of the metal surface plated upon, and the thickness of theplate applied, and these decorative nickel plates of various degrees ofsub-microscopic, micro scopic, and macroscopic satin texture and lusterwhen overlaid with a final thin chromium plate provide exceptionallyoutstanding corrosion protection to the underlying metal.

We have found that the addition to semi-bright and bright nickelelectroplating baths of bath-insoluble fine particles of water-insolubleinorganic oxygen-containing titanium and zirconium compounds containinga total of at least three different elements in these compounds andconsisting of powders of average particle size less than 5 microns anddown to colloidal dimensions will produce exceptionally highly corrosionresistant plate when given the usual final over-lay plate of about 0.01mil (0.25 micron) of chromium plate. These titanium and zir coniumcompounds comprise the class consisting of waterinsoluble titanates andzirconatcs of the metals including calcium, strontium, barium,magnesium, nickel, cobalt, iron, zinc, lead, cadmium, cerium, aluminum,antimony and bismuth, the zirconium and titanium silicates, mixtures andmixed compounds thereof, including, for example, the mixed compounds ofthe zirconates and titanates, the mixed zirconium and titaniumsilicates, such as the alkali metal titanium or zirconium silicates, thebarium, strontium and calcium titanium and zirconium silicates, as forexample, barium zirconium silicate and the mixed aluminates, titanatesand zirconates, as for example, zirconium spinel, etc. Evenconcentrations of the fine powders of only about 0.01 gram/liter willmake possible improved corrosion protection when the decorative platesobtained from these baths are given a final chromium plate of less thanabout 0.2 mil (5 microns). With most of these powders the maximumimprovement in corrosion protection in the less accessible recessedareas of articles is attained when about to 50 grams/liter of the finepowders are dispersed in the nickel baths, and further increase inconcentrations of powder until the baths become quite thick does notimprove the already exceptional corrosion resistance when a final thinchromium plate is applied. With the higher concentrations of powder theplates be come more satiny up to a point where further increase inconcentration of powder produces no further change in appearance of thenickel plate at a given nickel plate thickness on a given base and witha given brightener concentration in the nickel bath. In some cases, ashigh as about 500 grams per liter of fine powder can be dispersed in thebath, though in general about 250 grams/liter is the highest that isever needed for the most macroscopic satin plates.

The macroscopic satin-textured types of nickel plate which can beobtained by using the higher concentrations, e.g. about grams/liter orhigher of the afore-mentioned powders in the semi-bright and brightnickel electroplating baths are fine-grained lustrous satin nickeldeposits Which not only have a very pleasing appearance, but which canalso be high-lighted by buffing raised areas to give beautiful two-toneeffects, and which when chromium plated with about 0.01 mil chromiumplate will also provide exceptionally good corrosion protection to thebasis metals such as ferrous, aluminum, magnesium, brass, copper, zincand other metal articles.

The average particle diameter (herein sometimes referred to as particlesize") of the finely powdered bathinsoluble materials should not begreater than 5 microns. As some roughness, especially on shelf areaswhere particles can settle, may result from the use of materials ofparticle size greater than about 5 microns, the use of material ofparticle sizes less than 5 microns are preferred and are advantageous,with the most preferred particle size averaging about 0.02 to about 3microns as determined with the electron microscope. Some agglomeratedparticles may have larger particle size than 5 microns but withagitation in the nickel bath the larger agglomeratcs may be reduced to 5microns and under. Agitation is usually necessary to keep the finepowder suspended in the baths during plating. Air agitation ormechanical agitation including ultra-sonic agitation of the baths can beused.

Analysis of a satin nickel plate from an air agitated bright nickel bathcontaining superfine powdered material of particle size of about 0.02 to3 microns in concentrations even of about 100-200 grams/liter showsusually not higher than about 2.5% of the powdered material uniformlydistributed in the nickel plate, and with low concentrations of 10-20grams/liter or lower of the finest powders, as low as about 0.01% byweight is present in the nickel plate. Microscopic examination of thesurface of the plate shows an extremely uniform finely pitted surfacewhich consists of micro-inclusions and micro-pits. Calculations andmicroscopic examinations indicate that the number of micro-inclusionsand micro-pits per square centimeter of surface is at least of the orderof 10 This textured plate has excellent adhesion, for example, tonickel, ferrous, copper, and brass surfaces similar to that obtainedwhen the nickel bath contains none of the powdered material. Theleveling of the bright nickel plate is not decreased by the presence ofthe finely powdered additives. The throwing and covering power of theagitated bright nickel baths with the suspended powders is about thesame as without the fine powders present. It has been found that inplating articles with recessed areas and with shelf areas usingparticles of the preferred particle size, no objectionable roughness isobtained on the areas on which settling can occur, though in some caseswith the larger particle sizes, the shelf areas may be somewhat dullerthan the rest of the article, though this is usually negligible withshort plating times such as 30 seconds to about 5 minutes. With themacroscopic satin nickel the dulling is, of course, no problem.

The fine bath-insoluble powders plate out as uniform dispersions in thesemi-bright and bright nickel plate and thereby cause sub-microscopic(with the finest particles of 0.01 to about 0.05 micron size) tomicroscopic-inclusions and sub-microscopic to microscopic-pitting in thesurface of the nickel plate. That is at any given instant the surface ofthe semi-bright or bright nickel plate has distributed over its surfacemultitudinous fine particles in various stages of being imbedded in thesurface and causing sub-microscopic and microscopic pitting, and withthe thinnest plates (flashes or strikes) the pitting is mostlysubmicroscopic becoming more microscopically visible with thickerplating. When the usual chromium plate of about 0.01 mil (0.25 micron)chromium is applied to these submicroscopic to macroscopic satintextured surfaces a very fine favorable porosity pattern is developed inthe chromium plate which is the key to the extraordinary corrosionprotection afforded to the underlying metal by this compositenickel-chromium plate. With the very fine porosity pattern that isdeveloped in the thin chromium plate there is obtained the veryfavorable condition of tiny cathode areas, the chromium surrounding themultitudinous tiny anodes (the sub-microscopic and microscopic pits)which results in very weak corrosion currents with very low anodiccurrent densities in the corrosive environments. Thus, the penetrationof the corrosion pits towards the underlying basis metal is very greatlydiminished. There is also some evidence of extremely finestress-cracking of the chromium around the micro-inclusions which isalso favorable to forming micro cathodes and anodes. There is also thepossibility that with the thin chromium plate where most of themicro-inclusions and micro-pits are not completely plated over, that thechromium in the micro-pits may have some chromium chromate inhibitorformed in the micro-pits which would, besides the poorly conductingparticles, also be favorable to minimize the start of anodic attack.However, from the results obtained under prolonged severe corrosionexposure it is clear that it is the tiny cathode areas (chromium)surrounding the multitudinous tiny anode (nickel) areas that are the keyto the astounding corrosion protection afforded by the thin chromiumplated sub-microscopic-to-macroscopic-textured fine-grained nickeldeposits of this invention.

These textured nickel deposits give the best appearance and corrosionprotection results when plated on top of semi-bright sulfur-free nickelor bright nickel deposits. It is best and also simpler to use theregular semi-bright nickel plating baths for most of the plate and touse the minimum of the textured nickel plate required to obtain thedesired appearance and corrosion resistance, because the textured nickelplating bath requires added control due to the presence of the dispersedparticles, and also because the best corrosion protection results areobtained in this way.

The mechanism by which the particles plate out is not clear, theadsorption of hydrogen ions and nickel ions by the particles would givethe particles a positive charge and in this way they would tend to plateout. Also, under the powerful reducing conditions at the nickel cathode,it might be possible that the particles which are not semiconductorscould become semi-conductors by partial reduction. Nevertheless,independent of the mechanism of the plating out of these particles intothe nickel plate, it is amazing how readily these particles plate out ina surprisingly uniform manner in semi-bright and bright nickel plates.The plating out of the fine particles starts immediately and in thebright nickel plating baths there is evidence that the first layers ofnickel plated out actually contain somewhat higher concentrations of thefine powder than the subsequent ones. Also, the first layers may causemore micro-stress cracking in the thin chromium than the subsequentlayers.

The macroscopic satin nickel plate obtained from the agitated bright orsemi-bright nickel plating baths containing the higher concentrations ofthese fine powders can as already mentioned be easily buffed to a highluster, without losing the exceptional corrosion resistance whenchromium plated. Thus, the beautiful two-tone effects achieved bybuffing accessible portions of the macroscopic satin nickel platedobject still have the highest corrosion resistance after the finalchromium plate. Another useful decorative effect can be obtained wherebrush or 4 polishing lines are desired in a satin finish, by usingcoarse polishing grit, for example, to emery on the basis metal. Theoriginal coarse polishing lines, although diminished by the highleveling satin nickel plate, are still visible. In this way, a highlycorrosion resistant scratch brush finish satin nickel is obtainedwithout having to resort to scratch brushing a final nickel plate andthus greatly decreasing its corrosion protection.

Before technical grade powders are used commercially they should alwaysbe checked first in small scale tests such as in 1-4 liter baths beforebeing added to large baths because certain harmful impurities such asmetallic powders or too coarse particles may be present which will causerough plate, especially on shelf areas, but otherwise technical gradefine powders normally produce results similar to those obtained from theuse of high purity grades of the same particle size and structure. Also,if the powder is not wetted properly by the nickel bath, it should bewashed with solvents and checked for freedom from fatty or oily films.

In general, bright or semi-bright nickel plating baths of the Watts,sulfate, high chloride, sulfamate or fluoborate type, or mixtures can beused. While boric acid is the buffer usually used, other buffers, suchas formates. acetates, succinates or citrates may also be employed.

The pH of the baths may be from about 2 to 6, though the preferred pHvalues are from about 3.5 to 5.2. The temperature of the baths can befrom room temperature to at least 80 C., though in general a temperatureof about 55 C. to about 65 C. is preferred.

The best addition agents or brighteners to achieve the semi-bright andbright nickel plating conditions necessary to obtain the lustrous satintextured nickel after the addition to the bath of the afore-mentionedpowders are the following: the sulfur-containing brighteners includingaromatic and unsaturated aliphatic sulfonic acids, sulfonamides andsulfonimides, such as the benzeneor naphthalene-sulfonic acids,p-toluene sulfonimide, benzene sulfonamide, o-benzoyl sulfimide, vinylsulfonic acid, allyl sulfonic acid, 2-butyne-1, 4-disulfonic acid,o-sulfobenzaldehyde, etc.; the addition agents which produce semi-brightsulfur-free nickel plate such as formaldehyde, chloral hydrate, bromalhydrate, coumarin, butyne diol, adducts of butyne diol, used alone or incombination; combinations of unsaturated addition agents containingunsaturated linkages such as it o C=C, C=N, CEC, CEN, with organicsulfur-containing brighteners, organic sulfon-compounds, andcombinations of the latter with small concentrations of amines, such asquinaldine, p-olyamines or unsaturated amines such as N-allylisoquinolinium bromide, or other quaternaries of pyridines or quinolinesor isoquinolines.

Cobalt and iron can be present in the nickel bath as cobalt or ferroussulfates, chlorides, bromides, sulfamates or fiuoborates inconcentrations as high as at least 40 grams/liter, yielding nickel alloyplates containing concentrations of cobalt and/or iron up to a total ofabout 50% and it is to be understood that, except when the contextrequires otherwise, the expression nickel plate" as used herein coverssuch nickel alloy plates.

Surface active agents may be present in the baths, but are not usuallynecessary in the air agitated baths.

The maximum increase in lustrous sheen is obtained when the fine powdersare used in the agitated full bright nickel plating bath such as theair-agitated bright nickel plating baths possessing good levelingproperties. Less luster is obtained when the nickel baths contain only acarrier type brightener such as a benzene or naphthalene sulfonic acid,p-toluene sulfonamide, benzene sulfonamide or o-benzoyl sulfimide. Inthe latter cases the luster is flatter. This is also true when thesemi-bright sulfur-free type of addition agent such as formaldehydecoumarin,

chloral hydrate or bromal, is used solely with the fine powders, andwith these semi-bright addition agents it is usually best to use theultra-fine particle size powders of less than 0.5 micron particle size,and preferably less than 0.5 micron particle size as determined with theelectron microscope.

The sub-microscopic to macroscopic satin-textured nickel plate acceptschromium plate like regular nickel plate, and in general only the usualthicknesses of final chromium layer need be used, that is 0.25 micronthough thicknesses of 2.5 or 5 microns may be used. Besides, thedecorative nickel finish as such, or with the usual final chromiumfinish, the microscopic to marcoscopic satintextured nickel plate can begiven a rhodium, silver, tin, brass, bronze, copper, gold, or tin-nickel(65-35) alloy or other final thin coating. Thin wax, resin, or solublewax, films or clear lacquers greatly decrease finger marking of thefinal coatings, such as nickel, bronze, silver or brass coatings.Chromium, rhodium, and tin-nickel alloy plate do not need these organiccoatings, at least not for tarnishing effects.

Below are listed examples of baths of this invention in which one ormore of the above described powdered materials may be used as describedherein. It is to be understood that other inorganic bath compositionsand other brighteners may be used, though one of the preferred class ofbrighteners is the organic sulfon-oompounds.

Example I Grams/ liter Strontium titanate and/or zirconate (SrTiO SrZrO0.05 to 3 micron av.

particle size 0.1-100 NiSO -6H O 200-300 NiCl -6H O 40-120 H BO 40o-Benzoyl sulfimide 1-4 p-Tol uene sulfonamide 1-2 Allyl sulfonic acidl-4 2-butyn'oxy-1, 4-diethane sulfonic acid 0.05-0.2

pH=3.5-5.2, temp. some 0. Air agitation.

Example II Barium titanate and/or zirconate 0.1 to 3 micron av. particlesize 0.2-100 NiSO -6H O 200-300 NiCl '6H O 40-80 H BO 40 Benzenesulfonamide l-3 Allyl sulfonic acid 1-4 N-allyl quinaldinium bromide0.003-0.0l

pH=3.S-5.2, temp -0-70 C. Air agitation or mechanical agitation.

Example III Zirconium silicate (ZrSiO Example IV Cerium titanate and/ orzirconate av. particle size 0.1 to 3 microns 0.2-150 NiSO -6H O 50-150NiCl -6H O 200- H BO 40 o-Benzoyl sulfimide 2-4 N-allyl isoquinoliniumbromide 0.003-0.01 pH::3.5-5.2, temp, 50-70 C. Air agitation.

Example V Strontium titanate and/or zirconate av. particle size 0.05-3microns 0.2-100 NiSO -6H O 200-300 NiCl -6H O 30-60 H BO 40 Bromaland/0r chloral hydrate 0.05-0.1 Formaldehyde 0.02-0.08

pH=3.5-5.2, temp, 50-65 C. Air agitation or mechanical agitation.

Example VI Strontium titanate and/or zirconate av. particle size of0.05-3 microns 0.2-10 Ultra-fine silica powder (Quso) 1-50 NiSO -6H O200-300 NiCl -6H O 30-100 H BO 40 o-Benzoyl sulfimide 0.1-3 Benzenesulfonamide 1-3 Allyl sulfonic acid 1-4 Z-butynoxy-l, 4-diethanesulfonic acid 0.05-0.2

pH=3.5-5.2, temp, 50-70 C. Air agitation or mechanical agitation.

When the ultra-fine particles of about 0.01 to 0.05 micron sizeparticles are used in the semi-bright and bright nickel electroplatingbath, it is diflicult to see the included particles in cross-section ofthe nickel plate even at the highest magnification of the lightmicroscope. However, on the surface of the plate using strong light itis possible to just see the microscopic pitting effect of thesesub-microscopic particles. The thinner the plate that is deposited on abright surface, the more difiicult is it to distinguish any differencebetween the appearance of the textured deposit and the bright plateobtained without the particles present. With increasing thickness of thedeposit and with increasing concentrations of the fine particles, themicro-inclusions and micro-pitting can be more easily discerned, and anincreasing degree of visible satin texture of the plate occurs. Thus, inthe above examples of baths of this invention, the lower concentrationsof powder of 0.2 to about 20 grams/liter, and in some cases even toabout 50 grams/liter are best for obtaining bright plate from the brightnickel baths, and can thus be used best for very thin plates of about0.01 to 0.1 mil thickness on top of regular bright nickel or semibrightnickel plate to obtain after the final chromium plate very highcorrosion protecting bright plate. Using the CASS and Corrodkoteaccelerated corrosion tests, many cycles are passed with only 0.6 mil ofregular bright nickel or semi-bright nickel that is given a thin plate(0.01 to 0.1 mil) from the baths illustrated in the above examples, anda final 0.01 mil chromium plate; whereas, with regular bright nickelalone of the same total plate thickness and the same final thin chromiumplate, not one cycle is passed. With the higher concentrations of powderand with thicker deposits (0.2 mil to 0.5 mil) the plate becomes moremacroscopically satin-textured, and the extremely excellent corrosionprotection is maintained when the same thin final chromium plate isapplied. Again, the best corrosion protection results are obtained whenthe textured plate of this invention is applied on top of regular nickelplate which can be dull, semi-bright or bright nickel plate depending onthe decorative effect desired. That is, the degree of brightness,smokiness, or satin quality is dependent on the original brightness andsmoothness of the surface plated upon, as well as the thickness of theplate applied, the concentration and type of brighteners present, theconcentration of the powder in the bath, the particle size of the powderand the type of powder, that is, its chemical constitution. As anillustration of the latter, barium titanate at a given concentration,for example, of 20 grams/liter and with an average particle size of, forexample, 0.5 to 3 microns, will give a more macroscopic satin nickelplate than will strontium titanate at the same concentration and of thesame average particle size and from the same bright nickel bath. Byincreasing the concentration of the strontium titanate or by using lowerconcentrations of the brighteners, then the degree of macroscopic satintexture will be more closely alike. Furthermore, magnesium titanate ofthe same average particle size will require even higher concentrationsof the powder to produce the same degree of macroscopic satin texture asthe strontium titanate, or conversely strontium titanate and even moreso magnesium titanate will allow a full bright plate from the brightnickel bath at higher concentrations of powder than will bariumtitanate.

The nickel brighteners that produce very high leveling and brillianceas, for example, those given in US. 2,647,866 (Aug. 4, 1953) and U.S.2,800,440 and 2,- 800,443 (July 23, 1957) will produce the highestbrilliance with the powders dispersed in these bright nickel baths. Forless luster, either the higher concentrations of the powders can be usedin the very bright plating baths or lower concentrations or with justthe organic sulfoncompounds present as brighteners. These latterbrighteners such as o-benzoyl sulfimide, oor p-toluene sulfonamide,naphthalene, mono-, di-, or tri-sulfonic acids, etc., can be used inconcentrations ranging from about 0.1 gram/ liter to saturation.

In the case of barium, strontium and calcium titanates and zirconates,in the sulfate containing nickel baths such as the Watts nickel bath,there is also formed to a certain extent the insoluble sulfates of thesealkaline earth metals from the slight solubility of the titanates andzirconates in the acidic bath. However, this causes no problems inappearance effects or corrosion resistance results, and in the case ofstrontium zirconate and titanate it seems to be a beneficial effect inthat the mixed strontium sulfate, strontium titanate or strontiumzirconate fine particles give extremely excellent corrosion protectionresults even in very deeply recessed areas where the plate is very thinand is just barely covered with the final chromium plate. Many mixturesof fine powders as well as mixed fused powders give very good results,especially for the best distribution of micro-inclusions and micro-pitsin recessed areas. For example, strontium zirconate with zirconiumsilicate; aluminum oxide with zirconium silicate; ferric oxide orferrates or aluminates with titanates or zirconates. With ultra-finesilica which is the best powder for sub-microscopic pitting and theleast dulling eifects excellent results can be obtained. For example,with strontium titanate it is best to use about 5 to 50 grams per literof very fine silica to about 0.05 to 1 gram per liter of 0.1 to 3 micronstrontium titanate to obtain sub-microscopic to microscopic texturedfully bright nickel plate from the bright nickel bath and formacroscopic textured semibright nickel to use 1 to grams per liter ofthe very fine silica powder to about 10 to 50 grams per liter of: thestrontium titanate, or zirconate.

To achieve the highest possible corrosion protection results with thetextured decorative nickel plate of this invention on complex shapedarticles such as many zinc die-cast articles, for example, rear viewmirror holders, intricate light housings, steel bumpers, hub caps, andgrilles, it is best to use duplex or dual nickel underneath the texturednickel deposit. Thus, the total nickel deposit would consist ofsemi-bright sulfur-free nickel followed by regular bright nickelfollowed by a thin textured nickel deposit of this invention. The latterbeing used as thin plate (0.01 to about 0.1 mil) if the highestbrilliance is desired, or as a thicker plate with more powder in thebath to obtain a more subdued brightness or satin type of finish ifdesired. When ductile copper plate is used under nickel plate that has afinal coating of the textured decorative nickel plate of this invention,then the copper plate also helps in the total corrosion resistanceunlike the case when copper is used as a substitute for part of thebright nickel thickness in deposits of copper-bright nickel and theusual 0.01 mil thick final chromium. It is believed that this beneficialeffect of copper is also due to the tiny cathode areas developed in thefinal thin chromium plate, which in turn is due to the fine favorableporosity pattern developed in the thin final chromium plate as a resultof its being deposited over a decorative nickel surface containingmultitudinous sub-micro to micro-inclusions and sub-micro to micro-pitsof the order of 10 per sq. cm.

A particularly desirable and extremely corrosion resistant compositeplate is formed by electroplating the nickel plate of this invention onthe upper layer of the composite nickel coating described and claimed incopending application Serial No. 103,296, filed April 17, 1961, which isassigned to the assignee of this invention now US. Patent 3,090,733,issued May 21, 1963. This composite plate comprises a lower nickel platehaving an average thickness of about 0.15 mil to about 1.5 mils and anaverage .sulfur content less than about 0.03%, a first overlyingelectroplate of nickel, or nickel-cobalt alloy containing at least about50% nickel and having a thickness of about 0.005 mil to about 0.2 miland an average sulfur content of about 0.05% to about 0.3%, a secondoverlying layer of nickel or nickel-cobalt alloy containing at leastabout 50% nickel having a thickness of about 0.15 mil to about 1.5 milsand an average sulfur content of about 0.02% to about 0.15%, the secondoverlying layer containing a lower percentage of sulfur than said firstoverlying nickel electroplate and a higher percentage of sulfur thansaid lower nickel plate, an overlying layer of the nickel plate of thisinvention, and a top or upper layer of chromium having a thickness lessthan about 5 microns. In this composite plate, the fine grain nickelplate of this invention may vary from a thin flash layer to the thickerplate characterized as the macroscopic satin textured plate, but eventhe thin flash plates of this invention in such composite plate giveexcellent corrosion resistance.

Certain of the titanates tend to raise the pH of the nickel baths to pHvalues around 5.5, as for example, magnesium titanate, iron titanates,and it is therefore best to use these higher pH values with suchpowders. The copper, zinc, cadmium, lead, antimony and bismuth titanatesand zirconates must be used with much more careful control than theother powders to avoid an excess of free copper, zinc, lead, etc., ionswhich are known to be harmful to the quality of the nickel deposit, andthus it is best to use these powders at the lowest concentrations (0.1to 1 gram/liter) for the microscopic satin-textured lustrous nickelplate, and to use the higher pH values of the nickel bath to minimizesolubilization. In general, the preferred powders are the calcium,strontium, barium, magnesium, nickel, cobalt, iron, cerium and aluminumzirconates and titanates, zirconium silicate, and the calcium,strontium, magnesium, and barium zirconium silicates, and the best ofthese are the strontium and barium zirconates and titanates, zirconiumsilicate, and the strontium and barium zirconium silicates. Thesepowders are by far the least critical to use from the standpoint oftheir concentrations in the baths, the pH values of the baths, e.g. 36,and give optimum results for both microscopic and macroscopicsatin-textured lustrous nickel plate.

What is claimed is:

1. A method for electrodepositing a decorative nickel plate whichcomprises the step of electrolyzing an aqueous acidic solution of atleast one nickel salt selected from the group consisting of nickelsulfate, nickel chloride, nickel fluoborate and nickel sulfamate and atleast one soluble organic addition agent capable of producing semibrightto fully bright nickel plate, said solution containing dispersed thereinabout 0.1 to about 250 grams/liter of at least one material selectedfrom the class consisting of the water-insoluble oxygen-containingtitanium and zirconium compounds containing a total of at least threedifferent elements, said material being in the form of a fine powderhaving an ultimate particle size less than about 5 microns averagediameter, thereafter plating on said electrodeposited layer an overlayerof a metal se lected from the group consisting of chromium, rhodium,silver, tin, brass, bronze, copper, gold, and an alloy consisting of 65tin and 35 nickel, said overlayer having a thickness less than about 5microns.

2. A method for electrodepositing a decorative nickel plate whichcomprises the step of clectrolyzing an aqueous acidic solution of atleast one nickel salt selected from the group consisting of nickelsulfate, nickel chloride, nickel fluoborate and nickel sulfamate and atleast one soluble organic addition agent capable of producing semibrightto fully bright nickel plate, said solution containing dispersed thereinabout 0.1 to about 250 grams/liter of at least one material selectedfrom the group consisting of the waterinsoluble titanates and zirconatesof a metal selected from the group consisting of calcium, strontium,barium, magnesium, nickel, cobalt, iron, and aluminum, the zirconium andtitanium silicates, and mixtures and mixed compounds thereof, saidmaterial being in the form of a fine powder having an ultimate particlesize of less than about 5 microns average diameter, thereafter platingon said electrodeposited layer an overlayer of a metal selected from thegroup consisting of chromium, rhodium, silver, tin, brass, bronze,copper, gold, and an alloy consisting of 65 tin and 35 nickel, saidoverlayer having a thickness less than about 5 microns.

3. A method in accordance with claim 1 wherein said fine powder isstrontium titanate.

4. A method in accordance with claim 1 wherein said fine powder isbarium titanate.

5. A method in accordance with claim 1 wherein said fine powder iszirconium silicate.

6. A method in accordance with claim 1 wherein said fine powder isstrontium zirconate.

7. A method in accordance with claim 1 wherein said fine powder isbarium zirconate.

8. A method in accordance with claim 1 wherein said fine powder isbarium zirconium silicate.

9. A method in accordance with claim 1 wherein the metal of saidoverlayer is chromium.

10. A method for electrodepositing a decorative nickel plate whichcomprises the step of electrolyzing an aqueous acidic solution of atleast one nickel salt selected from the group consisting of nickelsulfate, nickel chloride, nickel fluoborate and nickel sulfamate and atleast one soluble organic addition agent capable of producingsemi-bright to fully bright nickel plate, said solution containingdispersed therein about 0.1 to about 250 grams/ liter of a mixture of atleast one material selected from the group consisting of thewater-insoluble titanates and zirconates of a metal selected from thegroup consisting of calcium, strontium, barium, magnesium, nickel,cobalt, iron, and aluminum, the zirconium and titanium silicates, mixedcompounds thereof and about 1 to about 50 gnams/ liter of finely dividedsilica powder, said materials being in the form of fine powders havingan ultimate particle size of less than about 5 microns average diameter,thereafter plating on said electrodeposited layer an overlayer of ametal selected from the group consisting of chromium, rhodium, silver,tin, brass, bronze, copper, gold, and an alloy consisting of 65 tin and35 nickel, said overlayer having a thickness less than about 5 microns.

11. A method in accordance with claim 2 wherein said nickel plate iselectrodeposited directly on an electrodeposit consisting essentially ofnickel.

12. A method in accordance with claim 2 wherein said dissolved organicnickel brightener is selected from the group consisting of aromatic andunsaturated sulfonic acids, sulfonamides and sulfonimides.

13. A method in accordance with claim 2 wherein said dissolved organicnickel brightener is o-benzoyl sulfimide.

14. A composite electroplate on a metal surface susceptible toatmospheric corrosion which comprises a nickel plate with chromiumoverplate, said nickel plate having been electrodeposited from an acidicnickel plating bath containing dissolved therein at least one organicnickel brightener capable of producing semi-bright to fully brightnickel plate, and having dispersed in said bath at least 0.1 gram/literof at least one water-insoluble powder material selected from the classconsisting of the waterinsoluble oxygen-containing titanium andzirconium compounds containing a total of at least three differentelements, said powder material having particles of average ultimateparticle size less than about 5 microns, and an electrodepositedchromium overlay plate on said nickel plate of less than about 5 micronsthickness.

15. A composite electroplate in accordance with claim 14 wherein saidnickel plate directly overlies an electrodeposit consisting essentiallyof nickel.

16. A composite electroplate in accordance with claim 14 wherein saiddissolved organic nickel brightener is selected from the groupconsisting of aromatic and unsaturated aliphatic sulfonic acids,sulfonamides and sulfonimides.

17. A composite electroplate on a metal surface susceptible toatmospheric corrosion which comprises a lower nickel electroplate havinga thickness of about 0.15 mil to about 1.5 mils and an average sulfurcontent less than about 0.03%, an overlying layer consisting essentiallyof an electroplate selected from the group consisting of nickelelectroplate and nickel cobalt alloy electroplate containing at leastabout 50% nickel and having a thickness of about 0.005 mil to about 0.2mil and an average sulfur content of about 0.05% to about 0.3%, anoverlying layer consisting essentially of an electroplate selected fromthe group consisting of nickel electroplate and nickel-cobalt alloyelectroplate containing at least about 50% nickel, and having athickness of about 0.15 mil to about 1.5 mils and an average sulfurcontent of about 0.02% to about 0.15%, the second overlying layercontaining a lower percentage of sulfur than the said first overlyingnickel electroplate and a higher percentage of sulfur than said nickelplate, an overlying layer of nickel plate electrodeposited thereon froman acidic nickel plating bath containing dissolved therein at least oneorganic nickel brightener capable of producing semibright to fullybright nickel plate and having dispersed therein about 0.1 to about 250grams/liter of at least one material selected from the class consistingof water insoluble oxygen-containing titanium and zirconium compoundscontaining a total of at least three different elements, said materialbeing in the form of a fine powder having an ultimate particle size lessthan about 5 microns average diameter, and an electrodeposited overlayerof a metal selected from the group consisting of chromium, rhodium,silver, tin, brass, bronze, copper, gold, and an alloy consisting of 65tin and 35 nickel, said overlayer having a thickness in the range ofabout 0.25 to about 5 microns.

(References on following page) 1 1 12 References Cited by the Examiner3,090,733 5/ 1963 Brown 20440 CIOOkS et a1. X

3/1956 M rid 204131 X JOHN H. MACK, Primary Examiner. 1351323 iiiiii5:331:35: 33333 2 5 HOWARD WILLIAMS, Examiner- 10/ 1962 Grazen 204-9 G.KAPLAN, Assistant Examiner.

14. A COMPOSITE ELECTROPLATE ON A METAL SURFACE SUSCEPTIBLE TOATMOSPHERIC CORROSION WHICH COMPRISES A NICKEL PLATE WITH CHROMIUMOVERPLATE, SAID NICKEL PLATE HAVING BEEN ELECTRODEPOSITED FROM AN ACIDICNICKEL PLATING BATH CONTAINING DISSOLVED THEREIN AT LEAST ONE ORGANICNICKEL BRIGHTENER CAPABLE OF PRODUCING SEMI-BRIGHT TO FULLY BRIGHTNICKEL PLATE, AND HAVING DISPERSED IN SAID BATH AT LEAST 0.1 GRAM/LITEROF AT LEAST ONE WATER-INSOLUBLE POWDER MATERIAL SELECTED FROM THE CLASSCONSISTING OF THE WATERINSOLUBLE OXYGEN-CONTAINING TITANIUM ANDZIRCONIUM COMPOUNDS CONTAINING A TOTAL OF AT LEAST THREE DIFFERENTELEMENTS, SAID POWDER MATERIAL HAVING PARTICLES OF AVERAGE ULTIMATEPARTICLE SIZE LESS THAN ABOUT 5 MICRONS, AND AN ELECTRODEPOSITEDCHROMIUM OVERLAY PLATE ON SAID NICKEL PLATE OF LESS THAN ABOUT 5 MICRONSTHICKNESS.